base64 编码 js

// 编码
const str = "Hello World!";
const encoded = btoa(str);
console.log(encoded); // "SGVsbG8gV29ybGQh"

// 解码
const decoded = atob(encoded);
console.log(decoded); // "Hello World!"

function utf8ToBase64(str) {
  return btoa(encodeURIComponent(str).replace(/%([0-9A-F]{2})/g, 
    function toSolidBytes(match, p1) {
      return String.fromCharCode('0x' + p1);
    }));
}

function base64ToUtf8(str) {
  return decodeURIComponent(atob(str).split('').map(function(c) {
    return '%' + c.charCodeAt(0).toString(16).padStart(2, '0');
  }).join(''));
}

const unicodeStr = "你好";
const encodedUnicode = utf8ToBase64(unicodeStr);
console.log(encodedUnicode); // "5L2g5aW9"

const decodedUnicode = base64ToUtf8(encodedUnicode);
console.log(decodedUnicode); // "你好"